1) Coaching the flying 200m via internet posts is like coaching a tennis serve...via internet posts. There are a lot of things involved and it's difficult to ID them (via self-reports) or the fixes via text. It's a lot more efficient for someone to help you on-site (teammate, coach, etc...). The best way for beginners to get up to speed (pun intended) by following a better rider (teammate, coach, friend).
2) The transition in and out of the saddle on a fixed gear bike simply requires practice. Drills will certainly help. You can even do this with your track bike locked into a trainer at home.
3) Comfort on the bike in and out of the saddle on the curves of the track are the foundation of everything. This comes with simply time- on-task. No amount of off-track training can shortcut this.
4) Times are not important right now. Don't put any stake in the numbers. They don't accurately reflect what you are capable of doing. Your same legs with the right gear, windup, jump, and bike handling will yield better results. Focus on those.